Session parameters
SESSION SET VALUE declares a parameter with an optional type and initializer. Queries refer to it using $name.
SESSION SET VALUE $minimum INTEGER NOT NULL = 30;MATCH (p:Person) WHERE p.age >= $minimum RETURN p.name AS name ORDER BY name;Parameter initializers have a restricted evaluator: literals, existing parameter references, graph references, supported unary expressions, lists and records. They do not execute arbitrary query expressions or nested queries.
SESSION SET GRAPH $g = social;USE GRAPH $g MATCH (p:Person) RETURN COUNT(*) AS people;The parser represents [PROPERTY] GRAPH <graph expression> and [BINDING] TABLE <binding table expression> reference values, including VARIABLE and parenthesized forms. Graph references resolve through the catalog. Driver-provided binding tables can be assigned through supported variable expressions, but nested-query binding-table initialization is not executed.
From Rust, set_parameter("minimum", Value::Integer(30)) supplies a decoded name without $. Only supported scalar/list families bind into ordinary query value expressions; a session Value variant does not imply general query support for that variant.
Regular, extended numeric and delimited parameter names are documented under identifiers.